Carbonyl compounds: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on 15B Carbonyl compounds (specification points 15.6–15.8), 2019–2025, with its mark scheme and examiner’s report.

All 93 questions on Carbonyl compounds, as a list

June 2025, Unit 4, Q1(a) (1 mark): Propanone reacts with hydrogen cyanide, HCN, in the presence of potassium cyanide, KCN. How is this reaction classified? (1) A electrophilic addition B electrop
June 2025, Unit 4, Q1(b) (1 mark): What is the first step in the mechanism of the reaction between propanone and a mixture of HCN and KCN? (1) A the lone pair of electrons on the carbon of CN− a
June 2025, Unit 4, Q1(c) (1 mark): What is the name of the organic product formed in part (a)? (1) A 2-hydroxy-2-methylpropylamine B 2-hydroxy-2-methylethylamine C 2-hydroxy-2-methylethanenitrile
June 2025, Unit 4, Q1(d) (1 mark): Which of these carbonyl compounds would produce pale yellow crystals when warmed with iodine in the presence of sodium hydroxide? (1) A butanone B butanal C pen
June 2025, Unit 4, Q1(e) (1 mark): What is the formula of the pale yellow crystals formed in part (d)? (1) A CI4 B CHI3 C CH2I2 D CH3I
June 2025, Unit 5, Q11(b) (1 mark): What type of reaction mechanism is taking place in step B? (1) A electrophilic addition B electrophilic substitution C nucleophilic addition D nucleophilic subs
June 2025, Unit 5, Q11(c) (1 mark): What are the reagents used in step B? (1) A KCN and NaOH B HCN and KCN C HCl and KNO2 D HNO3 and H2SO4
January 2025, Unit 4, Q16(b) (2 marks): Give a chemical test which distinguishes between pentan‑2‑one and pentan‑3‑one, CH3CH2COCH2CH3 . Include the results for both substances. (2)
January 2025, Unit 4, Q16(c) (2 marks): Give a different chemical test which distinguishes between pentan‑2‑one and pentanal, CH3CH2CH2CH2CHO . Include the results for both substances. (2)
January 2025, Unit 4, Q16(d) (3 marks): Pentan‑2‑one, pentan-3-one and pentanal react in a similar way with one test reagent to form solid products. Identify the reagent and describe how these solid p
January 2025, Unit 4, Q16(e) (4 marks): Pentan‑2‑one and pentan-3-one both react with hydrogen cyanide in the presence of KCN. With pentan‑2‑one a racemic mixture is formed but with pentan‑3‑one there
January 2025, Unit 6, Q3(a) (4 marks): Qualitative tests on X show that it • burns in air with a very smoky flame • forms an orange precipitate with 2,4-dinitrophenylhydrazine (Brady’s reagent) does
October 2024, AS Unit 3, Q3(b)(ii) (1 mark): The purified product was also treated with Fehling’s reagent. No colour change was observed. State the most likely conclusion that can be made from this informa
October 2024, AS Unit 3, Q3(c)(i) (4 marks): The purified organic liquid was refluxed with acidified potassium dichromate(VI) solution. A colour change was observed while refluxing. The resulting solution
October 2024, Unit 4, Q10(c) (1 mark): O and O (1) A warm each compound with Tollens’ reagent B add sodium carbonate solution to each compound C warm each compound with iodine under alkaline conditio
October 2024, Unit 4, Q14(a) (1 mark): What solvent is used in this reaction? (1) A ethanol B ether C ethyl ethanoate D water
October 2024, Unit 4, Q18(a)(i) (4 marks): Complete the mechanism for the reaction. Include curly arrows, the structure of the intermediate, and any relevant lone pairs and dipoles. (4) H3C slow C O H CN
October 2024, Unit 4, Q18(a)(ii) (2 marks): Explain why a small amount of sodium hydroxide solution is added to the reaction mixture, by considering the nature of the attacking species in the slow step. (
October 2024, Unit 4, Q18(d) (6 marks): Carbonyl compounds can be identified from their 2,4‑dinitrophenylhydrazine derivatives. Describe this process, including in your answer • observations you would
October 2024, Unit 5, Q19(d) (1 mark): The second step of the industrial preparation of the raspberry ketone involves the reduction shown. O O H2 catalyst HO HO Suggest why the choice of reducing age
June 2024, Unit 4, Q10 (1 mark): Propanone reacts with HCN in the presence of KCN. Which of these statements is incorrect? A CN– acts as a nucleophile in the reaction B a racemic mixture is for
June 2024, Unit 4, Q18(a) (4 marks): Propanal and propanone react similarly with lithium tetrahydridoaluminate(III). Complete the table about these reactions. (4) Formula of lithium tetrahydridoalu
June 2024, Unit 4, Q18(b) (2 marks): State what would be seen when separate samples of propanal and propanone are warmed with Tollens’ reagent. (2)
June 2024, Unit 4, Q18(c) (3 marks): When propanone reacts with iodine in the presence of aqueous sodium hydroxide, a yellow precipitate is observed. Write an equation for this reaction. Include st
June 2024, Unit 4, Q18(d) (3 marks): Propanal and propanone both react with 2,4‑dinitrophenylhydrazine. The products of these reactions may be used to distinguish between separate samples of propan
June 2024, Unit 4, Q18(e) (4 marks): Propanone, CH3COCH3, reacts with hydroxylamine, NH2OH, under mildly acidic conditions. The first stage of the reaction is a nucleophilic addition. Add curly arr
June 2024, Unit 6, Q1(b) (1 mark): Test 3 A few drops of A are added to 2 cm3 of Tollens’ reagent (ammoniacal silver nitrate solution). The mixture is placed in a warm water bath. Observation sil
June 2024, Unit 6, Q1(c)(i) (2 marks): Draw the displayed formula of the two structural isomers of A, using this information and your answers from (a) and (b). (2)
January 2024, Unit 4, Q11(b) (1 mark): Which reagent gives a positive result when added to carvone? (1) A ammoniacal silver nitrate (Tollens’ reagent) B aqueous sodium carbonate C iodine in the prese
January 2024, Unit 4, Q18(a) (2 marks): Name the reagent(s) in Step 1 and Step 2. (2) Step 1 Reagent(s) Step 2 Reagent(s)
January 2024, Unit 4, Q18(b)(i) (4 marks): Complete the mechanism for Step 1, using curly arrows and relevant lone pairs, charges and dipoles. (4) H H H C C O H –C N
January 2024, Unit 6, Q2(a) (2 marks): A sample of W gave a positive result with Tollens’ reagent. Give the positive result and the displayed formula of W. (2)
January 2024, Unit 6, Q2(c)(i) (2 marks): Give two observations of a positive result from this test. (2)
January 2024, Unit 6, Q2(c)(ii) (1 mark): Identify Y by name or formula. (1)
October 2023, Unit 4, Q14(a)(i) (1 mark): Give the IUPAC name of the organic product. (1)
October 2023, Unit 4, Q14(a)(ii) (4 marks): Complete the mechanism for this two‑step reaction, showing the structure of the intermediate and including curly arrows, and relevant lone pairs and dipoles. (4
October 2023, Unit 4, Q14(a)(iii) (2 marks): Justify the use of the term ‘nucleophilic addition’ to describe the mechanism of this reaction. (2)
October 2023, Unit 4, Q17(a) (6 marks): These four isomers can be identified using three chemical tests. Each test gives a positive result for only one isomer. All three tests give a negative result f
June 2023, AS Unit 3, Q2(c) (2 marks): 2 cm3 of Benedict’s or Fehling’s solution is added to separate 2 cm3 samples of each compound. The test tubes are placed in a warm water bath. Observations C D
June 2023, AS Unit 3, Q2(d)(i) (3 marks): Deduce the structure of C and the two possible structures of D. Use the molecular formula and the results from (a), (b) and (c). (3) Structure of C Possible str
June 2023, Unit 4, Q21(a) (2 marks): Complete the table for hexane-2,5-dione. Name the organic product formed if a reaction takes place. (2) Reaction Reagent and conditions Name of organic product
June 2023, Unit 4, Q21(b) (1 mark): State the observation when hexane-2,5-dione reacts with iodine in the presence of alkali. (1)
June 2023, Unit 4, Q21(c)(i) (1 mark): Name the type and mechanism of this reaction. (1)
June 2023, Unit 4, Q21(c)(ii) (1 mark): Draw the structure of the product. (1)
June 2023, Unit 4, Q21(d)(i) (1 mark): Give the observation when 2,4-dinitrophenylhydrazine (Brady’s reagent) reacts with hexane-2,5-dione. (1)
June 2023, Unit 4, Q21(d)(ii) (2 marks): Describe, in outline, how the product of this reaction may be used to confirm the identity of hexane-2,5-dione. Experimental details are not required. (2)
January 2023, Unit 4, Q15 (1 mark): Samples of ethanal and propanone are added to separate test tubes containing iodine dissolved in aqueous potassium hydroxide and the mixtures are heated gently.
January 2023, Unit 4, Q19(a) (1 mark): State the essential condition for using LiAlH4. (1)
January 2023, Unit 4, Q19(b) (4 marks): Complete the mechanism for the reduction of propanone with LiAlH4, showing the structure of the intermediate and of the final product. Include curly arrows, and
January 2023, Unit 4, Q19(c) (3 marks): Explain why LiAlH4 reduces carbonyl compounds but not alkenes, even though both types of compound have π bonds. (3)
October 2022, AS Unit 3, Q4(c)(iv) (4 marks): Give a further chemical test and the positive result for each of the oxidation products of propan‑1‑ol. (4)
October 2022, Unit 4, Q12 (1 mark): Which compound forms a precipitate with Fehling's or Benedict’s solutions and with iodine in the presence of alkali? A methanal B ethanal C propanone D butanone
October 2022, Unit 4, Q15(c)(ii) (4 marks): Complete the mechanism for the formation of X in Step 1. Include curly arrows, and any relevant lone pairs and dipoles. (4) O H CN–
June 2022, Unit 4, Q6 (1 mark): Which alcohol could not be formed by the reduction of an aldehyde or a ketone? A 2‑methylpentan‑1‑ol B 3‑methylpentan‑2‑ol C 3‑methylpentan‑3‑ol D 2‑methylpenta
June 2022, Unit 4, Q17(a) (3 marks): Three carbonyl compounds, A, B and C, are straight‑chain structural isomers, with the formula C5H10O. Only isomer A reacts with Tollens’ reagent to give a silve
June 2022, Unit 4, Q17(b)(i) (1 mark): Give the IUPAC name for CH3CH2CH(OH)CN. (1)
June 2022, Unit 4, Q17(c)(i) (1 mark): Propanone, an isomer of propanal, also reacts with HCN in the presence of KCN. Draw the skeletal formula of the product of this reaction. (1)
June 2022, Unit 5, Q14(b) (6 marks): Tests on samples of Q show that it • burns in air with a very sooty flame • forms an orange precipitate with Brady’s reagent (2,4-dinitrophenylhydrazine solutio
June 2022, Unit 6, Q2(a)(i) (3 marks): The student carries out three tests on separate samples of each compound. Complete Table 1 to show the observations that the student makes. (3) Observations on
June 2022, Unit 6, Q2(a)(ii) (1 mark): Identify, by name or formula, the pale yellow precipitate that forms when iodine and sodium hydroxide are added to a sample of D. (1)
June 2022, Unit 6, Q2(b)(i) (4 marks): The orange precipitates produced on the addition of Brady’s reagent to samples of C and E are called derivatives. The melting temperatures of derivatives are us
June 2022, Unit 6, Q2(b)(ii) (2 marks): The melting temperatures of the derivatives of the reaction of Brady’s reagent with some aldehydes and ketones are shown. Melting temperature of the derivative
January 2022, Unit 4, Q11 (1 mark): How many structural isomers with the molecular formula C5H10O react with Tollens’ reagent? A 2 B 3 C 4 D 5 Use this space for any rough working. Anything you wr
January 2022, Unit 4, Q12(a) (1 mark): The products of the reactions under the stated conditions include (1) Acidic conditions Alkaline conditions CH3I A CH3COO– CH3COCI3 B CH3COO– CH3COCH2I CH3I C C
January 2022, Unit 4, Q19(a)(i) (4 marks): Complete the mechanism for this reaction by adding curly arrows, and relevant lone pairs and dipoles to Step 1 and Step 2. (4) H H H H H H Step 1 O– H C C C H C
January 2022, Unit 4, Q20(b)(iii) (6 marks): A series of tests was performed on compound A. Test Observation 1 addition of phosphorus(V) chloride misty fumes 2 addition of 2,4‑dinitrophenylhydrazine orange
January 2022, Unit 5, Q10(b)(i) (2 marks): Complete the equation for the reaction. (2) OH OH O HO H + [Ag(NH3)2]+ + OH− OH OH glucose C6H12O7 + Ag + + Y
January 2022, Unit 5, Q10(b)(ii) (1 mark): Draw the structure of Y. (1)
January 2022, Unit 6, Q2(b) (3 marks): Three chemical tests are carried out on X. Test 1 When Brady’s reagent (2,4‑dinitrophenylhydrazine solution) is added to X, an orange precipitate is observed.
October 2021, Unit 4, Q12 (1 mark): An unknown aldehyde may be identified by measuring the melting temperature of the purified precipitate formed in its reaction with A 2,4-dinitrophenylhydrazine
October 2021, Unit 4, Q16(b)(ii) (3 marks): Give a chemical test which would allow you to distinguish between the two compounds you have given in (b)(i). Include the reagents required and the result for e
October 2021, Unit 5, Q21(b) (2 marks): Selenide anions attached to protein side‑chains may undergo nucleophilic addition reactions with curcumin. Complete the mechanism for one of the steps in such a
October 2021, Unit 5, Q21(e)(i) (2 marks): Complete the equation for this reaction. (2) O O H O O N + + + + 2 NaOH H2O N NO2 ONa H O
October 2021, Unit 6, Q2(a)(i) (2 marks): Complete the statements in the inference column by writing the names or formulae of the functional groups. (2) Test Observation Inference Test 1 A could contain
October 2021, Unit 6, Q2(a)(ii) (1 mark): Give the name or formula of the red precipitate formed in Test 2. (1)
June 2021, Unit 4, Q8(c) (1 mark): Four groups of students warmed samples of menthol with sodium dichromate(VI) in acid. They purified the reaction mixture and carried out a series of qualitative
June 2021, Unit 4, Q19(a)(i) (4 marks): Give the mechanism for Step 1. Include curly arrows, and any relevant lone pairs and dipoles. (4)
June 2021, Unit 6, Q3(b)(i) (2 marks): A and B O O OH OH O B A (2)
June 2021, Unit 6, Q3(b)(ii) (2 marks): C and D O O O C D (2)
January 2021, Unit 4, Q13 (1 mark): A compound X, with molecular formula C5H10O , gave an orange precipitate with 2,4-dinitrophenylhydrazine. X gave a silver mirror with Tollens’ reagent. Which of
January 2021, Unit 4, Q19(a) (1 mark): The skeletal formula of menthone is shown. O Give the molecular formula of menthone. (1)
January 2021, Unit 4, Q19(b) (4 marks): Ethanal, CH3CHO , reacts with hydrogen cyanide in the presence of cyanide ions to form 2-hydroxypropanenitrile. Draw the mechanism for this reaction. Include cu
January 2021, Unit 4, Q19(c)(i) (1 mark): F reacts with iodine in an alkaline solution to give a pale yellow precipitate. Give the name or formula of the group in F identified by this test. (1)
January 2021, Unit 4, Q19(c)(ii) (2 marks): Draw the skeletal formulae of the four possible structures of carbonyl compound F. (2)
October 2020, AS Unit 3, Q3(b) (4 marks): The organic liquid H is a pheromone thought to be involved in communication between rabbits. H O H3C CH3 State the initial and final appearance of each mixture
October 2020, Unit 4, Q10 (1 mark): Which diagram shows the first step of the mechanism for the nucleophilic addition of hydrogen cyanide to propanone in the presence of potassium cyanide? δ− O O–
October 2020, Unit 4, Q11 (1 mark): When propanone reacts with iodine in the presence of sodium hydroxide, the precipitate formed has the formula A CH3I B CHI3 C CH3COCH2I D CH3COCI3
October 2020, Unit 4, Q15(a) (1 mark): Which test would distinguish between 2-methylpropan-2-ol, (CH3)3COH, and butanone, CH3CH2COCH3? (1) A B C D
October 2020, Unit 4, Q15(c) (1 mark): Which test could not be used to distinguish between 2-methylpropan-2-ol, (CH3)3COH, and butanal, CH3CH2CH2CHO? (1) A B C D
October 2020, Unit 4, Q17(c)(ii) (1 mark): State the conditions required and the reagent needed to form compound W from propanal. (1)
January 2020, Unit 4, Q1(c) (1 mark): Which of these reacts with iodine and sodium hydroxide in solution to produce a pale yellow precipitate? (1) A compound 1 B compound 2 C compound 3 D compound 4
January 2020, Unit 4, Q17 (6 marks): *17 Compare and contrast the reactions of propanal and propanone with one oxidising agent, one reducing agent and 2,4-dinitrophenylhydrazine. In your answer inc
June 2019, AS Unit 3, Q2(b)(iii) (2 marks): A chemical test may be used to confirm the presence of an aldehyde. Identify the reagent used, giving the positive result of the test. (2)

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